Research On Function Of Crop-fruit Ecological System In Middle-South Of Loess Plateau

Based on principles of energy ecology and the theory of emergy, the agriculture subsystem, fruit industry subsystem, poultry industry subsystem and agro-fruit ecological system in Xipo village, Nan anshan village, Beigou village, Gaopo village in Shaanxi province the mid-south of the Loess Plauteau were chosen as research subject. Their structure characteristics, biomass and productivity, nutrient output-input balance, nutrient material cycles, energy flow and emergy analysis were carefully and systematically analyzed. An evaluating system was studied for comparison of ecological benefit, social benefit, economic benefit and the comprehensive benefits of each village peasant household on the characteristics of structure, function and benefits. The main conclusions were as follows:The agro-fruit ecological system was constructed with agricultural subsystem, apple fruit subsystem, poultry industry subsystem and human subsystem. The productivity of the peasant household agro-fruit ecological system was restricted by ratio of the agriculture, fruiter and poultry industry. The order of biomass productivity of each village peasant household agro-fruit ecological system is Beigou>Nan anshan>Xipo>Gaopo. The agricultural subsystem contributed 1.83%, apple fruit industry subsystem contributed 54.77% and poultry industry subsystem contributed 43.04%. The order of economic productivity of each village peasant household agro-fruit ecological system is Nan anshan>Xipo >Beigou >Gaopo. The agricultural subsystem contributed 2.33%, apple fruit industry subsystem contributed 91.63% and poultry industry subsystem contributed 6.04%. The apple fruit industry subsystem has an important role in the agro-fruit ecological system and should develop it sreadily.Compared with the conventional mode(without use of biogas slurry), the growth of apple tree could accumulated, the yield of apple fruit could increased and the quality of apple fruit could promote by use of biogas slurry. The fresh weight of 100 leaves increased by 4.90%, the length of branch of apple tree by 13.83%, the individual yield of apple tree by 7.42%, average fruit weight by 6.76%; solid substance, sugar, Vc and protein respectively increased by 12.68%,9.75%,14.34% and 22.00%, the acid decreased by 5.38%.The nutrient output-input budget of peasant household agro-fruit ecological system was N,P surplus, and K deficiency. The nutrient input of apple industry subsystem has main portion in the agro-fruit ecological because lots of fertilizer input. The N,P output was main output in agricultural subsystem, K was in apple industry subsystem. It could supply the N,P in agricultural subsystem and K in apple industry subsystem in order to make up the deficiency of nutrient. The poultry industry subsystem has little portion in the agro-fruit ecological system, so it should enforce development and supply sufficient organic fertilizer for agricultural and apple industry subsystem.In the peasant household agro-fruit ecological system, N,P,K absorption coefficient were separately 0.58%,0.06%,0.004%, the order of the peasant household was Xipo>Nan anshan>Beigou>Gaopo; cycling coefficient were 17.0%,13.3%,16.6%, the order of the peasant household was Nan anshan >Gaopo >Xipo >Beigou, indicated P cycling was more slowly; remnant coefficient were 83.0%,86.8%,83.4%, the order of the peasant household was Beigou>Xipo >Gaopo > Nan anshan; nutrient utilization rate were 5669.6,20914.4,6799.6, the order of the peasant household was Nan anshan > Beigou>Xipo >Gaopo; recycle period cycle were 7.39a,9.46a,8.84a, the order of the peasant household was Beigou > Xipo > Nan anshan >Gaopo.In the peasant household agro-fruit ecological system, the energy input and output were Beigou>Xipo>Nan anshan>Gaopo. The energy output (1.55×1012J/hm2.a) was bigger than the energy input(4.05×1011J/hm2.a). The ratio of energy output to input were Nan anshan (4.38)>Xipo(3.88)>Beigou(3.81)>Gaopo(3.25), the index of energy cycle was smaller (0.69), the structure of agro-fruit ecological system was not rational, so it should enforce the poultry development and increase the input of organic energy in order to ensure the sustainable development of the agro-fruit ecological system.In the peasant household agro-fruit ecological system, the emergy input of natural environmental resources were occupied the total emergy in Xipo village, Nan anshan village, Beigou village, Gaopo village respectively 15.81%,22.78%,26.23%,39.26%, the purchased emergy input were occupied respectively 84.26%,77.22%,73.77%,60.04%, indicated the purchased emergy input was main input in peasant household agro-fruit ecological system, and in different peasant household was Xipo>Nan anshan>Beigou>Gaopo. The order of solar emergy transformity was Nan anshan ( 3.92×105sej/J.a ) >Xipo(1.40)>Gaopo(1.13)> Beigou(8.13), indicated more emergy were input in Nan anshan peasant agro-fruit ecological system and the system hierarchy was higher than other three village. The net emergy yield ratio was Gaopo(1.66)>Beigou(1.35)>Nan anshan(1.29)>Xipo(1.18), the emergy input ratio was Xipo(5.32)>Nan anshan(3.39)>Beigou(2.81)>Gaopo(1.51), the environmental loading ratio was Xipo(11.15)>Nan anshan(8.56)>Gaopo(5.68)>Beigou(4.87), indicated the agro-fruit ecological system of Xipo and Nan anshan village peasant household have a better development, as the same time the environmental pressure were more serious, it should decrease the purchased emergy input and the cost of system production in order to realize the sustainable development.The social benefit, economic benefit, ecological benefit and comprehensive benefit were different in different peasant household agro-fruit ecological system. The order of social benefit was Beigou>Gaopo>Xipo>Nan anshan; the economic and the ecological benefit was Nan anshan>Xipo>Beigou>Gaopo; The comprehensive benefit was Nan anshan>Xipo> Beigou>Gaopo.